Claims
- 1. A gain control for a plurality of photomultipliers used in a gamma camera having an anode, a photocathode and a plurality of dynodes therebetween, said dynodes numbered sequentially from said photocathode to said anode with the first dynode adjacent said photocathode designated d.sub.n and any one specific dynode designated d.sub.n ;
- said photocathode connected to ground;
- a voltage divider resistor string extending from said anode to said photocathode, said string including a plurality of string resistors in series with one another extending from said anode to said photocathode and ground, each of said string resistors adjacent a dynode and numbered sequentially from said photocathode to said anode with the first one of said string resistors numbered r.sub.1 and the resistor adjacent said specific dynode d.sub.n designated r.sub.n each one of said string resistors separated from one another by a node;
- a source of constant DC voltage inputted to said string adjacent said anode;
- all of said dynodes connected to said string through a node adjacent each one's respective resistor except for said specific dynode d.sub.n which is isolated from said string, a first tap line connected to the node in said string adjacent said specific resistor r.sub.n whereby the voltage potential from said string associated with said dynode d.sub.n is applied to said first tap line thereby maintaining the integrity of said resistor string; and
- gain means electronically connected to said dynode d.sub.n and utilizing said voltage potential on said first tap line to apply a preset gain voltage potential to said dynode d.sub.n which can vary anywhere from said first tap line voltage potential to the string voltage potential at said dynode immediately adjacent said specific dynode d.sub.n on the dynode side closer to said photocathode and designated d.sub.n-1 whereby said preset gain voltage establishes the gain of said photomultiplier.
Parent Case Info
This is a continuation of application Ser. No. 247,063 filed May 20, 1994, now U.S. Pat. No. 5,493,610.
US Referenced Citations (12)
Foreign Referenced Citations (4)
Number |
Date |
Country |
0066763 |
Dec 1982 |
EPX |
0155377 |
Sep 1985 |
EPX |
1222536 |
Jul 1981 |
FRX |
851548 |
Jun 1960 |
RUX |
Continuations (1)
|
Number |
Date |
Country |
Parent |
247063 |
May 1994 |
|